联合主键

XML配置方法 
1.新建一个用于存放联合主键的类. 
2.配置映射文件 

 //新增存放联合主键的类.
 //需要实现序列化接口,覆盖hashCode和equals方法
 package com.meiyoudao.domain;

 import java.io.Serializable;

 /**
  *
  * @author meiyoudao
  *
  */
 public class PersonPK implements Serializable{


     private String name;
     private int id;
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     //需要覆盖hashCode 和 equals方法
     @Override
     public int hashCode() {
         StringBuffer strb = new StringBuffer();
         //返回联合主键的hashcode码
         //在map数组中能区分
         return strb.append(id).append(name).hashCode();
     }
     @Override
     public boolean equals(Object obj) {
         if(obj instanceof PersonPK){
             PersonPK o = (PersonPK)obj;
             if(o.id == this.id && o.name.equals(this.name)){
                 return true;
             }
         }
         return false;
     }


 }

 xml version="1.0"?>

         "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
         "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

 <hibernate-mapping package="com.meiyoudao.domain">

     <class name="Person">
         <composite-id name="personPK" class="PersonPK">
             <key-property name="id">key-property>
             <key-property name="name">key-property>
         composite-id>

         <property name="weight"/>
     class>

 hibernate-mapping>

Annotation配置的第一种方法 
1.新建一个存放主键的类.并声明这个类为@Embeddable 
2.在domain类中的get存放主键类的方法上,注解为@Id 

 package com.meiyoudao.domain;

 import java.io.Serializable;

 import javax.persistence.Embeddable;

 /**
  *
  * @author meiyoudao
  *
  */
 @Embeddable//可以被嵌入的
 public class PersonPK implements Serializable{


     private String name;
     private int id;
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     //需要覆盖hashCode 和 equals方法
     @Override
     public int hashCode() {
         StringBuffer strb = new StringBuffer();
         //返回联合主键的hashcode码
         //在map数组中能区分
         return strb.append(id).append(name).hashCode();
     }
     @Override
     public boolean equals(Object obj) {
         if(obj instanceof PersonPK){
             PersonPK o = (PersonPK)obj;
             if(o.id == this.id && o.name.equals(this.name)){
                 return true;
             }
         }
         return false;
     }


 }

 package com.meiyoudao.domain;

 import javax.persistence.Entity;
 import javax.persistence.Id;
 import javax.persistence.TableGenerator;

 @Entity
 public class PersonAnno {



     private String weight;
     private PersonPK personPK;
 @Id
 public PersonPK getPersonPK() {
         return personPK;
     }
     public void setPersonPK(PersonPK personPK) {
         this.personPK = personPK;
     }

     public String getWeight() {
         return weight;
     }
     public void setWeight(String weight) {
         this.weight = weight;
     }

 }

Annotation配置的第二种方法 
在domain类中的get存放主键类的方法上,注解为@EmbeddedId 

 package com.meiyoudao.domain;

 import javax.persistence.EmbeddedId;
 import javax.persistence.Entity;
 import javax.persistence.TableGenerator;

 @Entity
 public class PersonAnno {


     private String weight;
     private PersonPK personPK;
 @EmbeddedId
 public PersonPK getPersonPK() {
         return personPK;
     }
     public void setPersonPK(PersonPK personPK) {
         this.personPK = personPK;
     }
     public String getWeight() {
         return weight;
     }
     public void setWeight(String weight) {
         this.weight = weight;
     }

 }

Annotation配置的第三种方法(最适合开发习惯) 
1.新建一个存放主键的类 
2.在domain类中的主键get方法上,注解为Id(有几个注解几个) 
3.注解这个类为@IdClass(com.meiyoudao.domain.PersonPK.class)指定主键类 

 package com.meiyoudao.domain;

 import javax.persistence.Entity;
 import javax.persistence.Id;
 import javax.persistence.IdClass;

 @Entity
 @IdClass(com.meiyoudao.domain.PersonPK.class)
 public class PersonAnno {


     private int id;
     private String name;
     private String weight;

     @Id
     public int getId() {
         return id;
     }
     public void setId(int id) {
         this.id = id;
     }
     @Id
     public String getName() {
         return name;
     }
     public void setName(String name) {
         this.name = name;
     }
     public String getWeight() {
         return weight;
     }
     public void setWeight(String weight) {
         this.weight = weight;
     }

 }